1. Field of the Invention
The present invention is generally in the field of electrical circuits. More specifically, the invention is in the field of high-frequency switching circuits.
2. Related Art
High-frequency switching devices, such as high-frequency switching devices having multiple inputs and a shared output, can be used in mobile communication devices, such as cellular handsets, to provide operation at more than one frequency. For example, a high-frequency switching device can be used in a cellular handset operating in a system using a Global System for Mobile Communications (GSM) communications standard to enable the cellular handset to operate either at a low band frequency of 900.0 MHz or a high band frequency of 1800.0 MHz by selectively coupling a corresponding input to the shared output. For high-frequency switching devices, such as high-frequency switching devices used in mobile communication devices, there is a continuing need to reduce intermodulation distortion (IMD).
A conventional high-frequency switching device can include two or more switching arms, where each switching arm can include a number of field effect transistors (FETs) coupled between an input and a shared output of the switch. Each switching arm can be coupled to a control voltage input, which can provide a high voltage to enable the switching arm and a low voltage to disable the switching arm. In one approach, IMD can be reduced by increasing the number of FETs in each switching arm. However, increasing the number of FETs in each switching arm undesirably increases the semiconductor die area consumed by the switching device and signal loss in the switching device. In another approach, IMD distortion can be reduced by utilizing a charge pump to increase the high voltage that is utilized to enable the switching arms. However, this approach can undesirably increase the cost of the switching device.